[iSCSI] Produce meaningful errors on login failure

Return the most appropriate of EACCES, EPERM, ENODEV, ENOTSUP, EIO or
EINVAL depending on the exact error returned by the target, rather than
just always returning EPERM.

Also, ensure that error strings exist for these errors.

src/hci/strerror.c

 /** The most common errors */
 struct errortab common_errors[] __errortab = {
 	{ 0, "No error" },
-	{ ENOMEM, "Out of memory" },
+	{ EACCES, "Permission denied" },
+	{ ECANCELED, "Operation cancelled" },
+	{ ECONNRESET, "Connection reset" },
 	{ EINVAL, "Invalid argument" },
-	{ ENOSPC, "No space left on device" },
 	{ EIO, "Input/output error" },
-	{ EACCES, "Permission denied" },
-	{ ENOENT, "File not found" },
 	{ ENETUNREACH, "Network unreachable" },
-	{ ETIMEDOUT, "Connection timed out" },
-	{ EPIPE, "Broken pipe" },
-	{ ECANCELED, "Operation cancelled" },
+	{ ENODEV, "No such device" },
+	{ ENOENT, "File not found" },
 	{ ENOEXEC, "Not an executable image" },
+	{ ENOMEM, "Out of memory" },
+	{ ENOSPC, "No space left on device" },
+	{ ENOTSUP, "Not supported" },
+	{ EPERM, "Operation not permitted" },
+	{ ETIMEDOUT, "Connection timed out" },
 };

src/include/gpxe/iscsi.h

 #define ISCSI_OPCODE_LOGIN_RESPONSE 0x23
 
 /* Login response status codes */
-#define ISCSI_STATUS_SUCCESS		0x00
-#define ISCSI_STATUS_REDIRECT		0x01
-#define ISCSI_STATUS_INITIATOR_ERROR	0x02
-#define ISCSI_STATUS_TARGET_ERROR	0x03
+#define ISCSI_STATUS_SUCCESS			0x00
+#define ISCSI_STATUS_REDIRECT			0x01
+#define ISCSI_STATUS_INITIATOR_ERROR		0x02
+#define ISCSI_STATUS_INITIATOR_ERROR_AUTHENTICATION	0x01
+#define ISCSI_STATUS_INITIATOR_ERROR_AUTHORISATION	0x02
+#define ISCSI_STATUS_INITIATOR_ERROR_NOT_FOUND		0x03
+#define ISCSI_STATUS_INITIATOR_ERROR_REMOVED		0x04
+#define ISCSI_STATUS_TARGET_ERROR		0x03
 
 /**
  * iSCSI SCSI command basic header segment

src/net/tcp/iscsi.c

 	return 0;
 }
 
+/**
+ * Convert iSCSI response status to return status code
+ *
+ * @v status_class	iSCSI status class
+ * @v status_detail	iSCSI status detail
+ * @ret rc		Return status code
+ */
+static int iscsi_status_to_rc ( unsigned int status_class,
+				unsigned int status_detail ) {
+	switch ( status_class ) {
+	case ISCSI_STATUS_INITIATOR_ERROR :
+		switch ( status_detail ) {
+		case ISCSI_STATUS_INITIATOR_ERROR_AUTHENTICATION :
+			return -EACCES;
+		case ISCSI_STATUS_INITIATOR_ERROR_AUTHORISATION :
+			return -EPERM;
+		case ISCSI_STATUS_INITIATOR_ERROR_NOT_FOUND :
+		case ISCSI_STATUS_INITIATOR_ERROR_REMOVED :
+			return -ENODEV;
+		default :
+			return -ENOTSUP;
+		}
+	case ISCSI_STATUS_TARGET_ERROR :
+		return -EIO;
+	default :
+		return -EINVAL;
+	}
+}
+
 /**
  * Receive data segment of an iSCSI login response PDU
  *
 	if ( response->status_class != 0 ) {
 		DBGC ( iscsi, "iSCSI login failure: class %02x detail %02x\n",
 		       response->status_class, response->status_detail );
-		iscsi->instant_rc = -EPERM;
-		return -EPERM;
+		rc = iscsi_status_to_rc ( response->status_class,
+					  response->status_detail );
+		iscsi->instant_rc = rc;
+		return rc;
 	}
 
 	/* Handle login transitions */
 			return 0;
 		DBGC ( iscsi, "iSCSI %p unknown opcode %02x\n", iscsi,
 		       response->opcode );
-		return -EOPNOTSUPP;
+		return -ENOTSUP;
 	}
 }